Are mouse macro legal?I kinda want some official answer

Any form of modifications that are active while playing League are use at your own risk.

That being said, mapping one to one (i.e. mapping a "g key" on a logitech keyboard or an extra mouse button to one and only one other key) is not something that will be detected by Riot (as it's a computer side thing that doesn't "create" keypresses).

If you're going to map one key to more than one key (ex: to ward jump which would require two keys), that is not permitted and will be quite trivial to detect given how macros work.

I believe the current standing is one button is one button, so things like these are against the rules. I may be wrong, but I dont think I am.

Anything that can increase your gameplay performance is not allowed. That includes increasing click speed, 2 keys on the same button, programmed combos etc.

https://na.leagueoflegends.com/en/legal/termsofuse#code-conduct

#5. CODE OF CONDUCT ... ix. Using any unauthorized third party programs, including mods, hacks, cheats, scripts, bots, trainers and automation programs that interact with the Software in any way, for any purpose, including any unauthorized third party programs that intercept, emulate, or redirect any communication between the Software and Riot Games and any unauthorized third party programs that collect information about the Game by reading areas of memory used by the Software to store information; ...

The key here is programs. Macro buttons & keys must be programmed, thus they are automation programs (automating the press of multiple buttons/keys). You can remap any key you want to a different, single key, but you may perform that one, and only one, action.

it's fine, and basically undetectable anyway. These people don't understand how these kind of things work it seems. Same can be done with AutoHotKey.

No. This is essentially the same as any keyboard macro that would do the same thing, or scripting. It gives you an unfair advantage, is considered cheating, and will be detected easily.

Keeping it short because I know of too many people with specific mice//keyboard combos to put it any other way

Remapping A key is fine, Remapping MULTIPLE keys not fine. Remapping multiple keys is considered macroing, and because you can add delays, (or in some very specific cases) add cursor movement, right clicks, key command combos, its considered scripting

Any changes to your keybindings done via the ingae options menu are fine. The moment you use any third program to change ingame settings, you are at the risk of being permanently banned.

It really shoulödn't come as a suprise - of course you cant get such an advantage over your fellow players.